With the advance of technology and modern transportation, the propagation speeds of infectious diseases (e.g., SARS, avian flu, dengue fever and other diseases) are accelerated and become inestimable in today's world. Consequently, scientists are attempting to explore novel solutions for rapidly diagnosing, early isolation as well as suggested therapeutic treatment of suspected cases. In other words, a “real-time and in-situ detecting means” is an important issue to study infectious diseases.
In most practical application of fluid processing and regulating for clinical trials and diagnostics, such as protein purification and bacteria culture, a series of sample processing steps such as tissue dissociation, bacteria capture, cell lysis, nuclear acid extraction and washing, are always inevitable. Typically these processing steps require complex lab protocols and they are operated by skilled researchers with test tubes, pipettes and relevant equipment in a central laboratory.
“Lab-on-a-chip” is a novel concept proposed in recent years. In the lab-on-a-chip technology, various miniature components are integrated within a small platform so as to achieve the purposes of point of care (POC) and in vitro diagnostics (IVD). Essentially, it is a medical diagnostic platform with “miniature volume”, “high accuracy” and “real-time diagnostics”. Such platform could be effectively realized by microfluidic technology capable of processing various biological and chemical samples or reagents on a business-card-sized chip or cartridge.
On a typical microfluidic device, several common laboratory functions such as flow pumping, valving, mixing, heating and many reactions are compactly integrated on-chip and complex sample processing are normally programmable to realize automatic operations. However, most of lab-on-a-chip technologies developed in the laboratory is not appropriate for industrial applications. For example, in molecular diagnostics, the microfluidic chip used for sample testing requires low-cost, ease of mass production and disposable and therefore plastic chips made by injection molding or hot embossing are still prevalent. As the plastic microfluidic chip or cartridge is very hardly and in most situations unable to completely realize “lab-on-a-chip” functions, fluid dispensing and regulating within multiple chambers on microfluidic devices highly rely on various external pumps, valves, sensors and actuators. In most of these designs, each reagent chamber and microfluidic channel are regulated by one or more individual valves and therefore the isolation or connection of corresponding fluidic loop is solely controlled by the corresponding valve opening or closing.
Such designs, though being able to deliver fluid within the system, are very costly and normally occupy a huge amount of space. Moreover, the valves, the pumps and the microfluidic cartridge are most connected with tubing and therefore yield short lifespan, space consuming, low reliability and poor manufacturability and thus are inappropriate to high volume mass production. Furthermore, such solution is lack of modular design concept and is hardly to be straightforwardly used by other systems without redesign.
Besides, the rotary valve is widely used in many applications for dealing with multi-way fluid control. In order to prevent the rotary valve from leaking during its operation, compression force is always applied on the stator-rotor interface to provide a superior sealing. The forced sealing, though can minimize fluid leakage, actually introduces two issues suffered by most common rotary valves nowadays. First, when the valve turns from one position to the next, a high rotational torque is needed to overcome the friction between stator and rotor, and this requires a huge motor to be integrated. As a result, the size, cost and power consumption of the system increase. Second, because of the presence of friction, the wear and tear between stator and rotor significantly reduces the device lifespan after long-term usage.
Therefore, there is a need of providing a fluid control device in order to overcome the above drawbacks.